Browsing by Issue Date, starting with "2007-02-01"

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Covalently bonded polyhedral oligomeric silsesquioxane/polyimide nanocomposites and process for synthesizing the same
(2007-02-01)
Wei, Kuang-Hwa
;
Leu, Chyi-Ming
Polyhedral oligomeric silsesquioxane/polyimide nanocomposites with certain mechanical properties and low dielectric constant is synthesized by covalently tethering functionalized polyhedral oligomeric silsesquioxane molecules to polyimide. These nanocomposites appear to be self-assembled systems. A process for synthesizing said polyhedral oligomeric silsesquioxane/polyimide nanocomposites also is provided, comprising a step of forming porous type polyhedral oligomeric silsesquioxane, and a subsequent step of reacting with dianhydride or directly reacting with synthesized polyimide.
Three-dimensional thermoelectrical simulation in flip-chip solder joints with thick underbump metallizations during accelerated electromigration testing
(2007-02-01)
Liang, S. W.
;
Chang, Y. W.
;
Chen, Chih
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In flip-chip solder joints, thick Cu and Ni films have been used as under bump metallization (UBM) for Pb-free solders. In addition, electromigration has become a crucial reliability concern for fine-pitch flip-chip solder joints. In this paper, the three-dimensional (3-D) finite element method was employed to simulate the current-density and temperature distributions for the eutectic SnPb solder joints with 5-mu m Cu, 10-mu m Cu, 25-mu m Cu, and 25-mu m Ni UBMs. It was found that the thicker the UBM is the lower the maximum current density inside the solder. The maximum current density is 4.37 x 10(4) A/cm(2), 1.69 x 10(4) A/cm(2), 7.54 x 10(3) A/cm(2), and 1.34 x 10(4) A/cm(2), respectively, when the solder joints with the above four UBMs are stressed by 0.567 A. The solder joints with thick UBMs can effectively relieve the current crowding effect inside the solder. In addition, the joint with the thicker Cu UBM has a lower Joule heating effect in the solder. The joint with the 25-mu m Ni UBM has the highest Joule heating effect among the four models.
Evaluation research of polishing methods for large area diamond films produced by chemical vapor deposition
(2007-02-01)
Tsai, H. Y.
;
Ting, C. J.
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Chou, C. P.
;
機械工程學系
;
Department of Mechanical Engineering
The current study compared several polishing techniques of chemical vapor deposition (CVD) diamond films. Although research on various diamond polishing techniques has been carried for years, some issues still need to be examined in order to facilitate application on large areas in a cost-efficient manner. In the present work, microwave plasma enhanced chemical vapor deposition (CVD) was used to obtain diamond films with full width half magnitude (FWHM) less than 10 wavenummbers at 1332 cm(-1) Raman peak. The diamond films were processed through mechanical polishing, chemical-assisted mechanical polishing, thermo-chemical polishing, excimer laser ablation, and catalytic reaction assisted grinding. A profilometer, an atomic force microscope, and a scanning electron microscope have been used to evaluate the surface morphology of diamond Films before and after polishing. The results obtained by using the above mentioned techniques were analyzed and compared. (c) 2006 Elsevier B.V. All rights reserved.
Laboratory astrophysics in Taiwan
(2007-02-01)
Lin, G. -L.
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Liu, T. -C.
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Huang, M. A.
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Hwang, W-Y. P.
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Chen, C. -C.
We report the development of laboratory astrophysics program in Taiwan. We begin with outlining Taiwan's participation in the FLASH collaboration for measuring the fluorescence yield using SLAC 28.5 GeV electron beam. We then report the domestic effort of studying cosmic ray shower properties using NSRRC 1.5 GeV electron beam.
Optimum power-saving method for power MOSFET width of DC-DC converters
(2007-02-01)
Chen, K.-H.
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Chien, C.-C.
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Hsu, C.-H.
;
Huang, L.-R.
;
電控工程研究所
An optimum power metal-oxide-semiconductor field effect transistor (MOSFET) width technique is proposed for enhancing the efficiency characteristics of switching DC-DC converters. By implementing a one-cycle buck DC-DC converter, it is demonstrated that the dynamic power MOSFET width controlling technique has a much improved power reduction whether the load current is light or heavy. The maximum efficiency of the buck converter is similar to 92% with a 3% efficiency improvement for the heavy load condition. The efficiency is further improved by similar to 16% for the light load condition as a result of the power reduction from the large power MOSFET transistors. Also proposed is a new error-correction loop circuit to enable a better load regulation than that of previous designs. Compared with the adaptive gate driver voltage technique, the optimum power MOSFET width can achieve a significant improvement in power saving. It is also superior to the low-voltage-swing MOSFET gate drive technique for switching DC-DC converters.
Effect of oxygen concentration on characteristics of NiOx-based resistance random access memory
(2007-02-01)
Lee, Ming-Daou
;
Ho, Chia-Hua
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Lo, Chi-Kuen
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Peng, Tai-Yen
;
Yao, Yeong-Der
The resistance bistability and the switching effect has been systematically studied in nickel oxide films with variable oxygen concentrations. Both the switching bias voltage and the resistance ratio of RESET to SET were found to be strongly concentration dependent. Meanwhile, the electrical characteristics can be exactly examined by an Schottky emission. By means of mathematical fitting, the resistance bistability seems to be related to the alternating of dielectric constant and the barrier height. Furthermore, the room temperature cycle endurance with a distinguishable operation window was found to exceed 800. This indicates that the nickel oxide has the potential to be a promising material on resistance random access memory.
Fast and versatile algorithm for nearest neighbor search based on a lower bound tree
(2007-02-01)
Chen, Yong-Sheng
;
Hung, Yi-Ping
;
Yen, Ting-Fang
;
Fuh, Chiou-Shann
;
資訊工程學系
In this paper, we present a fast and versatile algorithm which can rapidly perform a variety of nearest neighbor searches. Efficiency improvement is achieved by utilizing the distance lower bound to avoid the calculation of the distance itself if the lower bound is already larger than the global minimum distance. At the preprocessing stage, the proposed algorithm constructs a lower bound tree (LB-tree) by agglorneratively clustering all the sample points to be searched. Given a query point, the lower bound of its distance to each sample point can be calculated by using the internal node of the LB-tree. To reduce the amount of lower bounds actually calculated, the winner-update search strategy is used for traversing the tree. For further efficiency improvement, data transformation can be applied to the sample and the query points. In addition to finding the nearest neighbor, the proposed algorithm can also (i) provide the k-nearest neighbors progressively; (ii) find the nearest neighbors within a specified distance threshold; and (iii) identify neighbors whose distances to the query are sufficiently close to the minimum distance of the nearest neighbor. Our experiments have shown that the proposed algorithm can save substantial computation, particularly when the distance of the query point to its nearest neighbor is relatively small compared with its distance to most other samples (which is the case for many object recognition problems). (c) 2005 Pattern Recognition Society. Published by Elsevier Ltd. All rights reserved.
A novel dilute antimony channel In0.2Ga0.8AsSb/GaAs HEMT
(2007-02-01)
Su, Ke-Hua
;
Hsu, Wei-Chou
;
Lee, Ching-Sung
;
Wu, Tsung-Yeh
;
Wu, Yue-Han
This letter reports, for the first time, a high-electron mobility. transistor (HEMT) using A dilute antimony In0.2Ga0.8AsSb channel, which is grown by a molecular-beam epitaxy system. The interfacial quality within the InGaAsSb/GaAs quantum well of the HEMT device was effectively improved by introducing the surfactantlike Sb atoms during the growth of the InGaAs layer. The improved heterostructural quality and electron transport properties have also been verified by various surface characterization techniques. In comparison, the proposed HEMT with (without) the incorporation of Sb atoms has demonstrated the maximum extrinsic transconductance g(m,max) of 227 (180) mS/mm, a drain saturation current density I-DSS of 218 (170) mA/mm, a gate-voltage swing of 1.215 (1.15) V, a cutoff frequency f(T) of 25 (20.6) GHz, and the maximum oscillation frequency f(max) of 28.3 (25.6) GHz at 300 K with gate dimensions of 1.2 x 200 mu m(2).
LQG controller for active vibration absorber in optical disk drive
(2007-02-01)
Chang, C. S.
;
Liu, T. S.
;
機械工程學系
;
Department of Mechanical Engineering
Unbalanced disks in rotation will lead to the main vibration of an optical disk drive. Passive vibration absorbers are usually used in current optical disk drives to suppress vibration. Generally, optical disk drives have to make a disk spin at multiple speeds by different read/write conditions. However, the passive vibration absorber only suppresses vibration at a specific rotating speed and may excite vibration at other speeds. This paper uses a linear quadratic Gaussian (LQG) controller for active vibration absorbers to reduce diskdrive vibration at multiple rotating speeds. The absorber with LQG control is validated based on simulation and experimental results.
Effect of gate sinking on the device performance, of the InGaP/AlGaAs/InGaAs enhancement-mode PHEMT
(2007-02-01)
Chu, L. H.
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Chang, E. Y.
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Chang, L.
;
Wu, Y. H.
;
Chen, S. H.
An enhancement-mode InGaP/AlGaAs/InGaAs pseudomorphic high-electron mobility transistor using platinum (Pt) as the Schottky contact metal was investigated for the first time. Following the Pt/Ti/Pt/Au gate metal deposition, the devices were thermally annealed at 325 degrees C for gate sinking. After the annealing, the device showed a positive threshold voltage (V-th) shift from 0.17 to 0.41 V and a very low drain leakage current from 1.56 to 0.16 mu A/mm. These improvements are attributed to the Schottky barrier height increase and the decrease of the gate-to-channel distance as Pt sinks into the InGaP Schottky layer during gate-sinking process. The shift in the V-th was very uniform across a 4-in wafer and was reproducible from wafer to wafer. The device also showed excellent RF power performance after the gate-sinking process.
The direct integral of some weighted Bergman spaces
(2007-02-01)
Chuah, Meng-Kiat
;
應用數學系
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Department of Applied Mathematics
Let G be the abelian Lie group R(n) x R(k)/Z(k), acting on the complex space X = R(n+k) x iG. Let F be a strictly convex function on R(n+k). Let H be the Bergman space of holomorphic functions on X which are square-integrable with respect to the weight e(-F). The G-action on X leads to a unitary G-representation on the Hilbert space H. We study the irreducible representations which occur in H by means of their direct integral. This problem is motivated by geometric quantization, which associates unitary representations with invariant Kahler forms. As an application, we construct a model in the sense that every irreducible G-representation occurs exactly once in H.
Effect of plasma treatment on the microstructure and electrical properties of MIM capacitors with PECVD silicon oxide and silicon nitride
(2007-02-01)
Ho, Chia-Cheng
;
Chiou, Bi-Shiou
;
電子工程學系及電子研究所
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Innovative Packaging Research Center
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Department of Electronics Engineering and Institute of Electronics
Metal-insulator-metal (MIM) capacitors with plasma enhanced chemical vapor deposited (PECVD) nitride exhibit trap-induced dispersive behavior and electrical hysteresis, which lead to degradation in capacitor linearity at low frequencies. The dominant defect was suggested to be silicon dangling bonds originated from nitrogen deficiency. Previous methods to eliminate the dispersive behavior and electrical hysteresis include use of oxide-nitride-oxide (ONO) stacks and/or plasma pre-treatment of silicon substrate before nitride deposition [Van Huylenbroeck S, Decoutere S, Venegas R, Jenei S, Winderickx G (2002) IEEE Electron Device Lett 23:191; Lau WS (1990) Jpn J Appl Phys 29:L690]. In this study, the plasma post-treatment method was employed; MIM capacitors with PECVD oxide and nitride were treated with N2O and SiH4/NH3 plasma, respectively, after deposition of the dielectric layer. No apparent change in film microstructure is observed after plasma treatment. Plasma post-treatment is effective in eliminating the electrical hysteresis shift of the nitride capacitors. Fourier transform infrared (FTIR) absorption spectra suggest an increase of the Si-H bond after SiH4/NH3 plasma bombardment of the nitride films. Auger depth profiling indicates a slight increase of nitrogen to silicon ratio after plasma treatment. The increase of the Si-H bonds as well as the raise of nitrogen to silicon ratio are two possible causes for the elimination of the hysteresis shift of the plasma-treated nitride capacitors. The time dependent dielectric breakdown testing indicates a decrease in both the leakage current and the lifetime of the MIM capacitors treated with plasma. Possible dielectric degradation mechanism is explored.
Optimization of the lens holder and yoke for a near-field optical pickup actuator to enhance frequency response
(2007-02-01)
Peng, Ming-Tsan
;
Huang, Hai-Jo
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Wu, Chun-Te
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Lee, Kwen-Jin
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Yang, Lei-Ming
A four-wire voice-coil actuator is designed and optimized for use in a near-field optical drive. The first objective was to design a lens holder which could accommodate a large-size lens module while possessing a strong mechanical structure. The second objective was to optimize the yoke so that the magnetic field would be uniform within the stroke range of the voice coils. These improvements eventually helped to improve the bandwidth of the frequency response of the actuator.
A 5.2 GHz 47 dB image rejection double quadrature Gilbert downconverter using 0.35 mu m SiGe HBT technology
(2007-02-01)
Wu, Tzung-Han
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Meng, Chinchun
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Wu, Tse-Hung
;
Huang, Guo-Wei
;
電信工程研究所
A 5.2 GHz 1 dB conversion gain, IP(1dB) = - 19 dBm and IIP(3)= -9dBm double quadrature Gilbert downconversion mixer with polyphase filters is demonstrated by using 0.35 mu m SiGe HBT technology. The image rejection ratio is better than 47 dB when LO=5.17 GHz and IF is in the range of 15 MHz to 45 MHz. The Gilbert downconverter has four-stage RC-CR IF polyphase filters for the image rejection. Polyphase filters are also used to generate LO and RF quadrature signals around 5 GHz in the double quadrature downconverter.
Simulation and analysis of metamorphic high electron mobility transistors
(2007-02-01)
Lin, Jia-Chuan
;
Yang, Po-Yu
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Tsai, Wei-Chih
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光電工程學系
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顯示科技研究所
In this paper, the metamorphic high electron mobility transistors (mHEMTs) are investigated numerically and compared with pseudomorphic high electron mobility transistors (pHEMTs). The two-dimensional device simulator, MEDICI, is used to solve the Poisson's equation and the electron/hole current continuity equations. The influences of delta-doping concentration and position, gate width, spacer thickness, etc. on the performances of HEMTs are explored. It shows clearly that mHEMTs have higher transconductances, drain currents and DC voltage swings than pHEMTs. (c) 2006 Elsevier Ltd. All rights reserved.
A floating gate design for electrostatic discharge protection circuits
(2007-02-01)
Chou, Hung-Mu
;
Lee, Jam-Wen
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Li, Yiming
;
電信工程研究所
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友訊交大聯合研發中心
In this paper, a circuit design method for electrostatic discharge (ESD) protection is presented. It considers the gate floating state for ESD protection and negatively gate biased for leakage suppression under normal operations. The circuit is achieved by adding a switch device and a negatively biased circuit at the gate of ESD protection devices. Robustness and leakage of ESD protection circuit are improved. The circuit suits thin thickness of gate oxide of complementary metal oxide semiconductor (CMOS) devices due to an elimination of oxide damage. This approach benefits design of very large-scaled integration circuit and implementation of system-on-chip with sub-100 nm CMOS devices. (c) 2006 Elsevier B.V. All rights reserved.
Simultaneous identifications of the minimum effective dose in each of several groups
(2007-02-01)
Jan, Show-Li
;
Chen, Yuh-Ing
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Shieh, Gwowen
;
交大名義發表
;
National Chiao Tung University
One primary goal in dose-response studies for drug development is to identify the minimum effective dose (MED) which is the lowest dose level with an effect that exceeds that of the zero dose control. In this paper, we consider step-down closed testing procedures on the basis of pairwise and Helmert contrasts suggested by Tamhane et al. [ Tamhane, A. C., Hochberg, Y., and Dunnett, C. W., 1996, Multiple test procedures for dose finding. Biometrics, 52, 21 - 37.] for the situation where one wishes to make all such MED identifications simultaneously in each of several groups. An example is given to illustrate the proposed tests. The Monte Carlo studies are further implemented to compare the relative error rate and power performances of the proposed tests.
Impacts of gate recess and passivation on AlGaN/GaN high electron mobility transistors
(2007-02-01)
Chan, Chih-Yuan
;
Lee, Ting-Chi
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Hsu, Shawn S. H.
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Chen, Leaf
;
Lin, Yu-Syuan
In this study, the impacts of gate recess and passivation on AlGaN/GaN high electron mobility transistors (HEMTs) were investigated. The trap-related characteristics were studied in detail by several different measurements including dc current-voltage, cur-rent collapse, gate lag, and flicker noise characterizations. With a Cl-2/Ar-recessed gate, drain current collapse factors (Delta I-max) of similar to 37.5 and similar to 6.9% were observed before and after SiN passivation. The gate lag measurements showed that the lagging phenomena almost disappear with SiN passivation for both Cl-2- and Cl-2/Ar-recessed devices. However, the flicker noise measurements revealed distinct noise levels of devices with different processes even after passivation. As the gate voltage (VG) changed from 2 to -4V, the devices recessed by Cl-2 exhibited lower drain noise current densities (S-ID/I-D(2) ranging from 2.8 x 10(-14) to 1.7 x 10(-12) Hz(-1) at 1 kHz) than those etched by Cl-2/Ar mixture gas (S-ID/I-D(2) ranging from 6.3 x 10(-14) to 6.0 x 10(-12) Hz(-1) at 1 kHz), whereas the devices without the recess process showed the lowest noise levels (S-ID/I-D(2) ranging from 2.8 x 10(-15) to 1.3 x 10(-13) Hz(-1) at 1 kHz). It was found that S-ID/I-D(2) increased monotonically when V-G changed from 2 to -4V. A bias dependence of the 1/f(gamma) slope gamma was observed, and a relatively large variation in the range of similar to 1.1 to 1.6 was found for devices recessed by Cl-2/Ar mixture gas. The number fluctuation model was employed to explain the observed trends. The results also indicated that the surface traps play an important role in these devices.
Design of memory sub-system with constant-rate bumping process for H.264/AVC decoder
(2007-02-01)
Li, Chih-Hung
;
Peng, Wen-Hsiao
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Chiang, Tihao
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資訊工程學系
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電子工程學系及電子研究所
In this paper, we propose an efficient memory sub-system and a constant-rate bumping process for a H.264/AVC decoder conforming to High profile@ Level 4. To efficiently utilize the throughput of external DRAM a synchronization buffer is employed as a bridge for reformatting the read/write data exchanged between the on-chip hardware and the off-chip DRAM In addition, we optimize the issues of read/write commands and adaptively enable the auto-precharge function by monitoring the motion information of a submacroblock. Furthermore, a regulation buffer with size comparable to the decoded picture buffer is created to ensure a constant output rate of decoded pictures for any conformed prediction structures. Along with other modules, the proposed scheme is verified at system level using transaction level modeling (TLM) technique. Statistical results show that synchronization buffer of larger block size provides higher memory efficiency, less access cycles and power dissipation. However, the granularity of 8x8 block size provides better trade-off among cost, efficiency, power, and real-time requirement.
Design, fabrication, and control of components in MEMS-based optical pickups
(2007-02-01)
Chiu, Yi
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Chiou, Jin-Chern
;
Fang, Weileun
;
Lin, Yung-Jiun
;
Wu, Mingching
Small-form-factor optical pickups and disk drives have been an area of intense research since the rise of portable consumer electronic products. In current technology, most of the devices are manufactured by the precision assembly of discrete miniaturized optomechanical components. The assembly process can be simplified and cost reduced by using the batch fabrication processes developed in microelectro-mechanical systems (MEMS). In this paper, the fabrication and testing of optical and actuator components for a MEMS-based optical pickup are presented. A novel design methodology is also applied to the servo control system of the pickup.